Accesory belt tension?

[Drew99GT]

How tight should a person tighten the tension on accesory belts like water pump/alternator? I just got a new belt that drives the water pump and alternator. My Haynes manual says that you should measure the deflection in the middle of the belt (when firmly pressed) and it should deflect only 1/4 of an inch if the belt is less than 11 inches long between pullies. This is assuming you don't have one of those tension gauges. I measured it and tightned everything up and it seems too tight, and my alternator is squeeking. It says for the tension gauge that a brand new belt should be have 180lbs of tension Vs. 100 for a used belt. You guys have any secrets for belt tension? I know if you have them too tight you can mess up the bearings in the water pump and alternator.

[ May 19, 2003, 11:14 PM: Message edited by: Drew99GT ]

 

[joee12]

Drew, I know that this is not the answer you want, but I have always gone by the "feel" of the belt, not too tight, not too loose. It one one those things that you can't describe on a post. Sorry, Joe

 

[Schmoe]

Snug it up and then crank the engine and watch it. The whole idea from what I've learned is that the belt is going to vibrate a lot as you increase in rpm's. You don't want it so loose that the belt will vibrate enough and jump the pulley. Quarter to 1/2 inch sounds about right.

 

[Greaser]

I always go by the 90 degree method..never failed me yet.Find the longest run of the micro V..between altenator,compressor what ever..tighten the belt so you can just turn it 90 degrees(straight up) from the flat position..and it will be hard to get to the 90 position when you get there...if it's too easy to twist it to 90..it's too loose...can't get it there(45 degrees)..too tight...never failed me yet!

 

[Drew99GT]

Is it true that you can hurt the bearings in the water pump and alternator if you have too much tension?

 

[Greaser]

quote:

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Originally posted by Drew99GT:
Is it true that you can hurt the bearings in the water pump and alternator if you have too much tension?

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If the belt is so tight that it starts to ruin bearings on accessories it will stretch before that happens...there are too many contact areas on a micro V ...it's turning alot of items...and is has a larger surface area as compared to the older single belt...the older belts running one pump or accessory if over tightened will cause problems but the micro V belt will just not live a long happy life if over tightened.

 

[JohnBrowning]

Here is the thing. A tension guage is a good training tool kind of like traiing wheels on a bike. Once you develop a feel for it you seldom use the guage. 1/4 of deflections sonds about right. You can always tighten a slightly loose belt but once you over tighten it and stretch it you can not go back! So if in doubt loosen it up a bit. 1 hour of driveing on a over tightened belt can damage it and shorten is usefull life. If you alternator is squeaking it is usualy the sound of the bearings going bad. If you think you hear a squeak check things like idler pulleys and for any grease or oil on any surfaces that come in contace with the belt. A water pump wearing makes an entirely different sound then an alternator bearing. If you do not have a good stethascope you can make due with long screw driver and use it to listen to each componet. This will let you isolate the sound much better. You simply touch the screw driver tip to the part( be careful) and then touch your ear to the handle.